CN109705892B

CN109705892B - Method for preparing alkane with same carbon number by catalytic hydrodeoxygenation of fatty acid and/or fatty acid ester

Info

Publication number: CN109705892B
Application number: CN201910036980.3A
Authority: CN
Inventors: 张颖; 郭子薇; 王昊
Original assignee: University of Science and Technology of China USTC
Current assignee: University of Science and Technology of China USTC
Priority date: 2019-01-15
Filing date: 2019-01-15
Publication date: 2020-06-26
Anticipated expiration: 2039-01-15
Also published as: CN109705892A

Abstract

The invention provides a method for preparing fatty acid andthe method for preparing the alkane with the same carbon number by catalytic hydrodeoxygenation of the fatty acid ester comprises the following steps: in a reaction container, in the presence of a catalyst, under the low temperature of 100-300 ℃ and the low hydrogen pressure of 0.1-5 MPa, the fatty acid and/or the fatty acid ester and hydrogen are subjected to hydrodeoxygenation reaction to obtain the required alkane product with the same carbon number. The present invention is made by utilizing Me as defined herein, preferably further modified by an active metal_aX_bAl_cThe composite catalyst of the composite catalyst and the solid acid catalyst is used for preparing the alkane with the same carbon number by catalytic hydrodeoxygenation of fatty acid and/or fatty acid ester, has the advantages of high conversion rate, simplicity in regulation and control, good selectivity, mild reaction conditions, convenience in catalyst preparation and the like, and has a very good industrial application prospect.

Description

Method for preparing alkane with same carbon number by catalytic hydrodeoxygenation of fatty acid and/or fatty acid ester

Technical Field

The invention relates to the technical field of compound preparation, in particular to a method for preparing alkanes (including straight-chain alkanes and branched-chain alkanes) with the same carbon number by catalytic hydrodeoxygenation of fatty acids and/or fatty acid esters.

Background

The alkanes, especially long alkanes with more than 6 carbon atoms, not only have important application value in the fields of medicine, pesticide, national defense and the like, but also have no separation from the alkanes in transportation fuels and laboratory solvents in daily life. With the rapid development of the automobile industry, the demand of the modern society for high-octane gasoline is increasing. And the popularization of new Euro III and Euro IV fuel oil standards puts higher requirements on the production of clean fuels. In order to meet the environmental requirements, the quality of gasoline must be developed in the direction of low aromatics, high octane number, low vapor pressure, lead-free and high oxygen content.

The focus of the research on the isomerization of the alkane is the catalyst, and the obtaining of the catalyst with high activity, high selectivity of the isomerization product and high stability is the premise of applying the related technology to production. The production of fuel in the world is mainly from the refining process of petroleum, and with the great consumption of petroleum resources and the increasing emphasis on environmental protection, the research on renewable biofuel has become a hot topic. The biological aviation kerosene belongs to renewable green energy sources, generally takes renewable biomass as a raw material, and the products are straight-chain saturated alkane, isoparaffin, aromatic hydrocarbon components and the like of C9-C16. The production of biological aviation kerosene by using grease as a raw material is a great hot spot of current research and application. The current process for preparing aviation fuel by using renewable biomass as a raw material is mainly realized by two steps, wherein the first step is hydrogenation saturation and deoxidation reaction of the renewable biomass raw material; the second step is that the separated and purified normal paraffin is subjected to isomerization reaction or cracking reaction to generate isoparaffin and short-chain branched paraffin.

In a plurality of alkane isomerization catalysts, the bifunctional catalyst composed of a metal component and an acid carrier has good catalytic performance, the common acid carrier is a zeolite molecular sieve which mainly comprises X-type zeolite, Y-type zeolite and mordenite, and the metal component is selected from noble metals [ H.B.Du, C.Fairbridge, H.Yang, Z.Ring, appl.Catal.A,2005,294,1-21, etc. ]]Or a non-noble metal selected from Ni, Co, Mo, Fe, etc. [ Guingjun Wu, NanZhang, Weili Dai, Naijia Guan, and Landong Li, ChemSus chem 2018,11, 2179-2188]. Noble metals are used as main active metals, the conversion rate and the alkane selectivity of the reaction are high, but the loading capacity is high, the cost is high, and the large-scale application in industry is not facilitated. The non-noble metal is used as the active metal, the reaction conditions required by the non-noble metal are relatively harsh, and the problem of metal loss causes the instability of the catalyst, which is not beneficial to industrial production. Meanwhile, for the reaction of preparing alkane by catalyzing and deoxidizing fatty acid or fatty acid ester catalyzed by most of catalytic systems, the product is alkane with the same carbon number, and meanwhile, short-carbon-chain alkane is inevitably generated, so that the product is more in variety and is not beneficial to subsequent industrial utilization; and in the process of forming short-chain alkanes, CO is formed due to decarburization or decarboxylation₂And greenhouse gases such as CO cause influence on the environment, increase carbon emission and greatly reduce atom economy. CN 105001901A discloses a preparation method of aviation fuel. The first step 3 of the method uses Ni-Mo/gamma-Al₂O₃The catalyst is subjected to hydrodeoxygenation reaction, and then a Pt/SAPO-11 catalyst is used for isomerization reaction, the reaction temperature of the two steps is above 320 ℃, the reaction conditions are harsh, different catalysts need to be replaced in the two steps, and the operation is complex. CN101802145A discloses a process for the final production of isoparaffins (diesel components) from fats and oils as feedstock by conversion in two separate reaction zones, hydrodeoxygenation and hydroisomerization, by recycling a portion of the first and second reaction zone products to the two reaction zones, respectively, wherein the catalyst is nickel or one or more noble metals dispersed on a high surface area support, which is subjected to a two-zone conversionThe preparation process is relatively complex, and decarbonylation and decarboxylation reactions occur in the products in the reaction process, so that low-carbon paraffin is generated and CO are simultaneously generated₂The influence on the environment is caused, and the types of products are more, which is not beneficial to the subsequent separation.

Therefore, there is a need in the art to develop a method for efficiently producing alkanes of the same carbon number from fatty acids and/or esters under mild conditions and a novel catalyst system for the method which is highly stable and recyclable.

Disclosure of Invention

In view of the above, the present invention provides a method for preparing alkanes with the same carbon number by catalytic hydrodeoxygenation of fatty acids and/or fatty acid esters, the method comprising: in a reaction vessel, in the presence of a catalyst, at a low temperature of 100-300 ℃ and a low hydrogen pressure of 0.1-5 MPa, the fatty acid and/or the fatty acid ester and hydrogen are subjected to hydrodeoxygenation reaction to obtain a required alkane product with the same carbon number,

the catalyst is Me_aX_bAl_cA catalyst combination of a composite catalyst and a solid acid catalyst, wherein Me represents a metal selected from Cu, Co, Ni or Fe, X represents an oxide of a metal selected from Zn, Mg, Mn or Zr, Al represents an oxide of Al, and a, b and c represent the respective molar ratios of Me, X and Al and are values of 0.1 to 10, respectively; the solid acid catalyst is a molecular sieve, metal oxide or solid super acidic catalyst.

In a preferred embodiment, said Me is_aX_bAl_cThe composite catalyst is modified by active metal to further improve the stability, catalytic activity and cycle life of the composite catalyst, wherein the active metal is one or more selected from Pd, Ru, Pt, Co, Ir, Os, Rh, Ag and Cu; preferably, based on said overactive metal modified Me_aX_bAl_cThe content of the active metal is 0.01-10.0%, preferably 0.1-3.0% by weight of the composite catalyst.

In a preferred embodiment, said Me is_aX_bAl_cThe composite catalyst is subjected to pre-reduction treatment in hydrogen atmosphere before use, or in reverseThe in-situ reduction treatment is directly carried out in the hydrogen atmosphere of the container.

In a preferred embodiment, the fatty acid and/or fatty acid ester is a saturated or unsaturated C6-C22 fatty acid and/or fatty acid ester; preferably, the fatty acid is one or more selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, tetradecenoic-2-acid, palmitic acid, palmitoleic acid, hexadecanoic-2, 4-dienoic acid, palmitic acid, oleic acid, linoleic acid, stearic acid, arachidic acid, erucic acid and behenic acid; the fatty acid ester is one or more selected from methyl decanoate, methyl laurate, methyl palmitate, ethyl oleate, methyl oleate, ethyl stearate, jatropha oil, palm oil, coconut oil, cottonseed oil and illegal cooking oil; preferably, the feed molar ratio of the catalyst to the fatty acid and/or fatty acid ester is 1:1 to 100, preferably 1:10 to 100.

in a preferred embodiment, the molecular sieve is an HZSM-5 molecular sieve, an HY zeolite molecular sieve, an H β zeolite molecular sieve, a mordenite, an HX zeolite molecular sieve, a ZSM-35 molecular sieve, a SAPO-34 molecular sieve or a SAPO-11 molecular sieve, and the metal oxide is Al₂O₃、SiO₂Or Nb₂O₅(ii) a The solid super acid is SO₄ ^2-/ZrO₂、WO₃/ZrO₂Or MoO₃/ZrO₂。

In a preferred embodiment, the hydrodeoxygenation reaction is carried out at 100-200 ℃, preferably 140-200 ℃ under the hydrogen pressure of 1-4 MPa for 1-8 hours to obtain a main product of straight-chain alkane with the same carbon number; or, the hydrodeoxygenation reaction is carried out at 200-300 ℃, preferably 200-280 ℃ for 1-8 h under the hydrogen pressure of 1-4 MPa to obtain the main product of the branched alkane with the same carbon number.

In a preferred embodiment, the hydrodeoxygenation reaction is carried out in the absence of a solvent or in the presence of a solvent, and the hydrodeoxygenation reaction time is 0.5-24 hours; preferably, the solvent is one or more selected from the group consisting of water, acetone, n-hexane, methanol, ethanol, isopropanol, n-octane, ethyl acetate, methyl acetate, dodecane, and tetradecane.

In a preferred embodiment, said Me is_aX_bAl_cThe composite catalyst was prepared as follows: mixing soluble salts of metals Me, X and Al in water according to a composition molar ratio, and then adding an alkali solution to obtain a precipitate; the precipitate obtained is calcined and finally reduced to give the desired Me_aX_bAl_cA composite catalyst.

In a preferred embodiment, the active metal modified Me_aX_bAl_cThe composite catalyst was prepared as follows: mixing soluble salts of metals Me, X and Al in water in a compositional molar ratio, then adding an alkali solution to obtain a precipitate, and calcining the obtained precipitate to obtain Me_aX_bAl_cA complex; the obtained Me_aX_bAl_cThe complex is dispersed in an organic solvent, then a soluble salt of the active metal is added and mixed with sufficient agitation to load the active metal to Me_aX_bAl_cOn the complex; the obtained Me carrying active Metal_aX_bAl_cDrying the compound and reducing to obtain the required active metal modified Me_aX_bAl_cA composite catalyst.

In a further preferred embodiment, the alkali solution is a sodium hydroxide, potassium hydroxide, sodium carbonate or aqueous ammonia solution.

In a further preferred embodiment, the soluble salt is a nitrate, acetate or chloride salt.

In a further preferred embodiment, for dispersing said Me_aX_bAl_cThe solvent of the complex is water, ethanol, acetone, diethyl ether, toluene or xylene.

In a preferred embodiment, the combined catalyst is recycled.

The method for preparing the alkane completely reserves the fatty acid carbon chain in the hydrogenation process, has high conversion rate and simple regulation and controlGood selectivity, mild reaction condition, convenient catalyst preparation, recycling and the like, and has good industrial application prospect. In particular, the process of the invention is carried out by employing Me optionally modified with an active metal_aX_bAl_cThe combined catalyst solid phase catalytic system of the composite catalyst and the solid acid catalyst can efficiently convert fatty acid and/or fatty acid ester into required alkane with the same carbon number under the conditions of relatively low temperature and low pressure, for example, the raw material conversion rate of the method of the invention can reach 99.9 percent, the alkane selectivity can reach 99.6 percent, the isomerization rate can reach 98.0 percent, and the Me modified by active metal_aX_bAl_cThe solid phase catalyst system of the compound is obviously improved in the circulation, and simultaneously, the products are alkanes with the same carbon number, thereby reducing the separation cost of the products and being beneficial to industrial production. The method has the advantages of simple operation, good catalyst activity, high conversion rate, excellent selectivity, good stability and the like; after the reaction is finished, the solid-liquid two-phase separation is convenient, the catalyst can be used for many times, and the catalytic activity and the stability are still kept good. In addition, with the process of the present invention, the feedstock is not decarbonylated and decarboxylated during the reaction, thereby enabling improved atom economy and reduced carbon emissions.

Detailed Description

The invention relates to a method for preparing alkanes with the same carbon number by catalytic hydrodeoxygenation of fatty acids and/or fatty acid esters, comprising Me optionally modified by an active metal_aX_bAl_cUnder the combined catalytic action of the catalyst and the solid acid catalyst, the fatty acid and/or the fatty acid ester and hydrogen are subjected to hydrodeoxygenation reaction to obtain alkane compounds with the same carbon number, and by adjusting corresponding reaction conditions, straight-chain alkanes with mainly the same carbon number can be obtained at lower temperature and pressure, and branched-chain alkanes with mainly the same carbon number can be obtained at higher temperature and pressure. More specifically, the method of the present invention comprises: in a reaction container, in the presence of a catalyst, at a low temperature of 100-300 ℃ and a low hydrogen pressure of 0.1-5 MPa, the fatty acid and/or the fatty acid ester and hydrogen are subjected to hydrodeoxygenation reaction to obtain the required alkane product with the same carbon number。

In the method of the present invention, there is no particular requirement for a reaction vessel, and any reaction vessel known in the art, for example, a reaction vessel commonly used in the art, may be used as long as the hydrodeoxygenation reaction of the present invention can be achieved. For such a reaction vessel, a stirring device such as magnetic stirring and a heating device such as oil bath heating, a nitrogen gas cylinder for providing an inert atmosphere and a hydrogen gas cylinder for providing a hydrogen reaction atmosphere and pressure, and the like can be used in combination.

In the process of the present invention, the reaction raw material used is a fatty acid and/or a fatty acid ester (both of which may include natural fats and oils). As used herein, a fatty acid is a fatty carboxylic acid containing one or more carboxyl groups, preferably only one carboxyl group, and a fatty acid ester may be an ester of the aforementioned fatty acid, such as a fatty acid methyl ester or a fatty acid ethyl ester. Although the present invention is not particularly limited with respect to the structure and the number of carbon atoms of the fatty acid and/or fatty acid ester used, preferably, the fatty acid is one or more selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, tetradecenoic acid-2-enoic acid, palmitic acid, palmitoleic acid, hexadecanoic acid-2, 4-dienoic acid, palmitic acid, oleic acid, linoleic acid, stearic acid, linoleic acid, linolenic acid, stearic acid, arachidic acid, erucic acid and behenic acid; the fatty acid ester is one or more selected from methyl decanoate, methyl laurate, methyl palmitate, ethyl oleate, methyl oleate, ethyl stearate, jatropha oil, palm oil, coconut oil, cottonseed oil and illegal cooking oil. In particular, when the fatty acid or ester feedstock used contains unsaturated bonds, such as olefinic bonds, a saturated fatty alcohol product is obtained after the hydrodeoxygenation reaction of the present invention.

In the method of the present invention, the same-carbon alkane as the reaction product encompasses all the reaction products obtained by the catalytic hydrodeoxygenation reaction of the present invention of the above-described fatty acid and/or fatty acid ester, including the straight-chain or branched alkane obtained by the catalytic hydrodeoxygenation reaction of the present invention, which may be a single alkane or a plurality of alkanes. In the present invention, the alkane as the reaction product has a carbon number determined by the fatty acid and/or fatty acid ester as the reaction raw material, that is, the carbon number may be in the range of usually 6 to 22 carbon atoms. As used herein, the term "same carbon number" means the same carbon number as that of the raw fatty acid used, or the same carbon number as that of the fatty acid in the raw fatty acid ester used.

In the process of the invention, the catalyst used is Me_aX_bAl_cCo-catalyst of the composite catalyst and the solid acid catalyst.

Me used in the invention_aX_bAl_cIn the composite catalyst, Me represents a metal selected from Cu, Co, Ni or Fe, X represents an oxide of a metal selected from Zn, Mg, Mn or Zr, Al represents an oxide of Al, and a, b and c represent the respective molar ratios of Me, X and Al and are each a value of 0.1 to 10, which may be a decimal or an integer.

In the process of the invention, preferably, Me is increased further_aX_bAl_cStability, catalytic activity and recyclability of the composite catalyst, Me_aX_bAl_cThe composite catalyst is further modified by active metal, wherein the active metal used for modification is one or more selected from Pd, Ru, Pt, Co, Ir, Os, Rh, Ag and Cu. In certain embodiments, the modified composite catalysts of the invention may be represented in the form of a supported catalyst "active metal/MeXAl" with the active metal supported on a MeXAl composite (where a, b, and c may be any desired values), e.g., one example of the composite catalyst of the invention modified with Pd may be abbreviated as Pd/Me_aX_bAl_c. In the present invention, the active metal may be supported on the MeXAl composite by a conventional method such as impregnation.

In the process of the invention, preference is given to using active metal-modified Me as the base_aX_bAl_cThe content of the active metal for modification is 0.01-10.0%, preferably 0.1-3.0% of the total weight of the composite catalyst.

In the process of the invention, preference is given to active metal-modified Me_aX_bAl_cThe composite catalyst is subjected to a pre-reduction treatment in a hydrogen atmosphere before use, or directly subjected to an in-situ pre-reduction treatment in a hydrogen atmosphere of a reaction vessel, thereby further ensuring that the metal Me and the active metal for modification are in their active states, and the catalyst has complete catalytic activity.

As the solid acid catalyst used in the present invention, it may be an acidic molecular sieve, a metal oxide, a solid super acid catalyst, etc. which are commonly used in the art, preferably, the acidic molecular sieve used may be an HZSM-5 molecular sieve, an HY zeolite molecular sieve, an H β zeolite molecular sieve, a mordenite, an HX zeolite molecular sieve, a ZSM-35 molecular sieve, a SAPO-34 molecular sieve, a SAPO-11 molecular sieve, etc. preferably, the metal oxide used may be Al₂O₃、SiO₂Or Nb₂O₅And the like. Preferably, the solid super acid used may be SO₄ ^2-/ZrO₂、WO₃/ZrO₂Or MoO₃/ZrO₂And the like. Such solid acid catalysts are all commercially available or may be prepared according to methods well known in the art.

In the process of the present invention, although not particularly limited, preferably, the feed molar ratio of the catalyst to the raw material fatty acid and/or fatty acid ester to be used may be 1:1 to 100, preferably 1:10 to 100.

In the process of the present invention, since the raw material fatty acid or fatty acid ester itself used can be used as a solvent, the hydrodeoxygenation reaction can be carried out in the absence of a solvent or in the presence of a solvent. Preferably, in the presence of a solvent, the solvent used may be one or more selected from the group consisting of water, acetone, n-hexane, methanol, ethanol, isopropanol, n-octane, ethyl acetate, methyl acetate, dodecane and tetradecane.

In the method of the present invention, although not particularly limited, the time of the hydrodeoxygenation reaction is preferably 0.5 to 24 hours, preferably 1 to 12 hours.

In the method, in order to obtain a product mainly comprising straight-chain alkanes with the same carbon number, the hydrodeoxygenation reaction is preferably carried out at 100-200 ℃, preferably 140-200 ℃ and under the hydrogen pressure of 1-4 MPa for 1-8 hours; in order to obtain a product mainly containing branched alkane with the same carbon number, the hydrodeoxygenation reaction is preferably carried out for 1-8 hours at 200-300 ℃, preferably 200-280 ℃ and under the hydrogen pressure of 1-4 MPa.

In the process of the invention, Me is used_aX_bAl_cThe composite catalyst may be prepared by methods known in the art. For example, it can be prepared by: mixing soluble salts of metals Me, X and Al in water according to a composition molar ratio, and then adding an alkali solution to obtain a precipitate; the precipitate obtained is calcined and finally reduced to give the desired Me_aX_bAl_cA composite catalyst.

In the process of the present invention, the modified composite catalyst used may be prepared by any method in the art. For example, the active metal modified Me of the invention_aX_bAl_cThe composite catalyst may be prepared as follows:

firstly, for example in a beaker, soluble salts of the metals Me, X and Al are mixed in water in the compositional molar ratio, then an alkaline solution is added to obtain a precipitate, and the obtained precipitate is calcined, for example in a muffle furnace, for example at 300 to 600 ℃ to obtain Me_aX_bAl_cA complex;

then, the obtained Me was_aX_bAl_cThe complex is dispersed in a suitable solvent, then a soluble salt of the active metal is added and mixed with sufficient agitation to load the active metal to Me_aX_bAl_cOn the complex;

finally, the obtained Me loaded with active metals_aX_bAl_cAfter the compound is subjected to solvent removal through rotary evaporation, for example, the compound is dried in an oven at 60-100 ℃ and subjected to reduction treatment to obtain the active metal modified Me_aX_bAl_cA composite catalyst.

In the above-mentioned preparation of the composite catalyst of the present invention, the alkali solution used is mainly for adjusting the pH of the reaction system, and examples thereof may be sodium hydroxide, potassium hydroxide, sodium carbonate, or an aqueous ammonia solution, etc.

In the above-mentioned preparation of the complex catalyst of the present invention, the soluble salt used may be a nitrate, acetate or chloride salt of the corresponding metal, etc., and is not particularly limited as long as it is soluble in the solvent used in the reaction system.

In the preparation of the above-mentioned composite catalyst of the present invention, Me used for dispersing is added_aX_bAl_cThe solvent for the complex is not particularly limited, and may be, for example, water, ethanol, acetone, diethyl ether, toluene, xylene, or the like.

Me optionally modified with active Metal, prepared by the above-described Process_aX_bAl_cThe composite catalyst and the solid acid catalyst have good catalytic activity and excellent stability, and can be recycled for multiple times.

Examples

To further illustrate the present invention, a detailed description is provided below with reference to examples.

Unless otherwise indicated, the procedures and steps involved in the following examples are conventional procedures and steps, and reagents and equipment used are commercially available and used without further treatment.

Modified or unmodified Me_aX_bAl_cPreparation of composite catalyst

Preparation example 1: unmodified Cu₆Zn₃Al₁Preparation of composite catalyst

In a beaker, Cu (NO) is added according to the molar ratio of Cu to Zn to Al of 6:3:1₃)₂·3H₂O、Zn(NO₃)₂·6H₂O and Al (NO)₃)₃·9H₂O was dissolved in 150mL of deionized water at 80 ℃. Then, Na was added₂CO₃The aqueous solution was added until the pH of the mixture solution was about 8. The mixture solution was stirred by a magnetic stirring device for about 1 hour, then aged at 80 ℃ for 15 hours, and a solid was obtained by filtrationAnd (4) precipitation of the body. The obtained solid was washed with deionized water and dried in a 105 ℃ dry box for 30 hours, and then calcined in a 350 ℃ muffle furnace for 6 hours, thereby obtaining calcined Cu₆Zn₃Al₁And (c) a complex.

Finally, calcined Cu will be obtained₆Zn₃Al₁Complexes in H₂Reducing at 280 deg.C for 3 hr in atmosphere, wherein the heating rate before reaction is 1.0 deg.C/min, H₂At a flow rate of 60mL/min, thereby obtaining the desired Cu₆Zn₃Al₁A composite catalyst.

Preparation example 2: other Me not modified_aX_bAl_cPreparation of composite catalyst

Preparation of other non-modified Me's, as referred to in tables 1 or 2 below, by a preparation procedure analogous to preparation 1_aX_bAl_cA composite catalyst.

Preparation example 3: Pd/Cu₆Zn₃Al₁Preparation of composite catalyst

In a beaker, Cu (NO) is added according to the molar ratio of Cu to Zn to Al of 6:3:1₃)₂·3H₂O、Zn(NO₃)₂·6H₂O and Al (NO)₃)₃·9H₂O was dissolved in 150mL of deionized water at 80 ℃. Then, Na was added₂CO₃The aqueous solution was added until the pH of the mixture solution was about 8. The mixture solution was stirred by a magnetic stirring device for about 1 hour, then aged at 80 ℃ for 15 hours, and a solid precipitate was obtained by filtration. The obtained solid was washed with deionized water and dried in a 105 ℃ dry box for 30 hours, and then calcined in a 350 ℃ muffle furnace for 6 hours, thereby obtaining Cu₆Zn₃Al₁And (c) a complex.

1.0g of Cu obtained above₆Zn₃Al₁The complex was placed in a beaker and acetone was added, heated to 45 ℃ by a water bath under magnetic stirring, then a solution of 0.0007g of palladium chloride dissolved in acetone was added dropwise and stirring was continued for 24 h. Then reduced pressure rotary evaporated to remove the solvent and dried in an oven at 80 deg.CTo obtain Pd/Cu loaded with metal Pd₆Zn₃Al₁And (c) a complex.

The obtained modified composite can be directly subjected to pre-reduction treatment in a hydrogen atmosphere before use or directly added into a reaction system for reduction treatment, thereby obtaining the Cu modified by the active metal Pd required by the invention₆Zn₃Al₁A composite catalyst, and wherein the active metal Pd content is 0.1 wt% based on the total weight of the composite catalyst (whereby the composite catalyst is expressed as Pd/Cu)₆Zn₃Al₁)。

Preparation example 4: Ru/Cu₃Mn₆Al₁Preparation of composite catalyst

Through a similar preparation process as that of preparation example 3, Ru/Cu with 0.1% Ru loading was prepared₃Mn₆Al₁A composite catalyst.

Preparation example 5: Ru/Cu₃Mg₆Al₁Preparation of composite catalyst

Through a similar preparation process as that of preparation example 3, Ru/Cu with 0.1% Ru loading was prepared₃Mg₆Al₁A composite catalyst.

Preparation example 6: Pd/Fe₁Zn₄Al₅Preparation of composite catalyst

Prepared by a similar preparation process as in preparation example 3 to obtain Pd/Fe with 0.3% Pd loading₁Zn₄Al₅A composite catalyst.

Preparation example 7: Pt/Ni₃Mn₆Al₁Preparation of composite catalyst

Pt/Ni with 0.5% Pt loading was prepared by a similar procedure as in preparation example 3₃Mn₆Al₁A composite catalyst.

Preparation example 8: Pd/Co₃Zn₆Al₁Preparation of composite catalyst

Prepared by a similar preparation process as in preparation example 3 to obtain Pd/Co with 0.3% Pd loading₃Zn₆Al₁CompoundingAnd (3) a catalyst.

Preparation example 9: Pd/Fe₁Zn₄Al₅Preparation of composite catalyst

Preparation example 10: other modified Me_aX_bAl_cPreparation of composite catalyst

A variety of other active metal modified Me's were prepared by a similar procedure as in preparation example 3, as referred to in tables 3-6 below_aX_bAl_cThe loading amount of active metal in the composite catalyst is respectively 0.1-3.0% (based on the modified Me)_aX_bAl_cThe total weight of the composite catalyst).

Application examples for the preparation of alkanes of the same carbon number from fatty acids (esters) 1: unmodified Me_aX_bAl_cThe composite catalyst and the composite catalyst composed of different solid acid catalysts are used for catalyzing fatty acid (ester) hydrodeoxygenation to prepare straight-chain alkane as a main product (the product can be directly determined whether the product is a straight-chain or branched-chain product through gas chromatography and mass spectrum detection results)

In a 25mL reaction vessel, 50mg of oleic acid and 5mg of Me prepared in preparation example 1 or 2 shown in Table 1 were added_aX_bAl_cThe composite catalysts (before use, these composite catalysts were each pre-reduced in a closed reaction vessel under a hydrogen atmosphere at room temperature for 3 hours) and 5mg of a solid acid catalyst were used as a combined catalyst, and then 10mL of n-hexane was added, heated to 200 ℃ under a hydrogen atmosphere of 2MPa and reacted for 8 hours under magnetic stirring. After the reaction was completed, the reaction solution was cooled to room temperature, and after discharging and evacuating, the reaction solution was diluted with n-hexane, and the catalyst solid was separated by centrifugation to obtain a reaction solution, and the obtained reaction solution was subjected to gas chromatography.

the conditions of gas chromatography analysis were GC99 gas chromatography, FID detector, capillary chromatography column (HP-530 m.times.0.320 mm.times.0.25 μm), temperature programmed, initial column box temperature 100 deg.C, temperature rise to 160 deg.C at a rate of 5 deg.C/min, and hold for 3 minutes, carrier gas was 99.99% high purity nitrogen, and flow rate was 1 mL/min.

The results of gas chromatography analysis of the catalyst used and the reaction using the same are shown in table 1, wherein the conversion and yield are calculated as follows:

TABLE 1

Application example 2: unmodified Me_aX_bAl_cComposite catalyst composed of composite catalyst and different solid acid catalysts for catalyzing fatty acid (ester) hydrodeoxygenation to prepare branched alkane as main product

The reaction and the result analysis were performed in the same procedure as in application example 1 except that the reaction temperature was increased to 240 ℃, wherein the catalysts used and the results of the gas chromatography analysis after the reaction to which they were applied are shown in table 2, and wherein the isomerization rate of alkanes was calculated by the following formula:

TABLE 2

Catalyst and process for preparing same	Conversion ratio of raw Material (%)	Total yield of alkane (%)	Paraffin isomerization ratio (%)
				Cu₆Zn₃Al₁+HZSM-5	91.2	88.0	84.3
Cu₆Mg₁Al₃+HY	93.2	92.3	84.3
				Cu₁Zn₄Al₅+Al₂O₃	93.2	86.0	80.2
Fe₅Mg₃Al₂+Hβ	91.5	90.4	85.3
				Cu₄Zn₅Al₁+HZSM-5	91.2	90.4	83.1
Ni₂Zn₂Al₃+Al₂O₃	95.0	92.4	84.1
				Cu₆Mn₃Al₁+ mordenite zeolite	90.7	89.8	80.1
Cu₄Mg₅Al₁+HZSM-5	97.2	86.6	82.4
				Cu₁Mn₅Al₄+HX	90.4	89.8	86.7
Ni₂Mn₇Al₁+HZSM-35	90.0	87.6	83.3
				Cu_2.5Mn₃Al₁+Al₂O₃	94.9	94.0	86.4
Cu₆Zr₃Al₁+ mordenite zeolite	94.7	94.1	81.7
				Ni₂Zr₃Al₃+HZSM-5	91.4	87.6	85.7
Cu₁Zr₄Al₅+Nb₂O₅	92.7	89.0	87.3
				Cu₃Zr₆Al₁+SiO₂	97.1	93.8	84.0
Cu₄Zr₅Al₁+WO₃/ZrO₂	95.8	87.4	84.6
				Co₆Zn₃Al₁+HZSM-5	97.8	86.6	83.4
Ni₅Zn₄Al₁+HX	95.8	85.6	84.0
				Co₄Zn₅Al₁+HY	94.4	90.9	83.9
Co₃Zn₆Al₁+HZSM-35	92.8	91.8	86.2
				Fe₂Zn₇Al₁+ mordenite zeolite	96.1	93.9	84.4
Co₁Zn₄Al₅+HZSM-5	96.2	94.0	84.8
				Co₆Zr₃Al₁+HZSM-5	96.6	85.3	80.7
Co_5.5Zr₃Al₁+WO₃/ZrO₂	91.3	89.1	85.6
				Fe₄Mg₃Al_2,5+HX	96.5	86.7	85.4
Co₂Zr₆Al₂+HZSM-35	91.2	88.0	84.3
				Fe₁Zr₃Al₆+ mordenite zeolite	93.2	91.3	84.3
Co₁Zr₄Al₅+MoO₃/ZrO₂	93.2	86.0	80.2
				Co₆Mn₃Al₁+HX	91.5	90.4	85.3
Ni₅Mg₃Al₂+HZSM-5	91.2	88.4	83.1
				Co₄Mn₄Al₂+ mordenite zeolite	95.0	94.4	84.1
Co₃Mn₆Al₁+HZSM-5	90.7	89.8	80.1
				Fe₂Mn₃Al₅+HZSM-35	97.2	86.6	82.4
Co₁Mg₃Al₆+SiO₂	94.4	91.8	86.7

Application example 3: modified Me_aX_bAl_cComposite catalyst composed of composite catalyst and different solid acid catalysts for catalyzing fatty acid (ester) hydrodeoxygenation to prepare straight-chain alkane as main product

Reactions and result analyses were performed in the same procedures as in application example 1, except that methyl laurate was used as a reaction raw material instead of oleic acid, a combined catalyst composed of various modified composite catalysts prepared in preparation example 10 and a solid acid catalyst as shown in table 3 was used, and n-octane was used as a solvent and a diluent, wherein the catalysts used and the results of gas chromatography analysis after the reactions using the same are shown in table 3.

TABLE 3

Application example 4: modified Me_aX_bAl_cComposite catalyst composed of composite catalyst and different solid acid catalysts for catalyzing fatty acid (ester) hydrodeoxygenation to prepare branched alkane as main product

The reaction and the result analysis were performed in the same procedures as in application example 3, except that the reaction temperature was increased to 240 ℃, wherein the catalysts used and the results of the gas chromatography analysis after the reaction using the same were shown in table 4, and wherein the isomerization rate of alkane was calculated by the following formula:

TABLE 4

Application example 5: modified Me_aX_bAl_cComposite catalyst composed of composite catalyst and different solid acid catalysts for catalyzing fatty acid (ester) hydrodeoxygenation to prepare straight-chain alkane as main product

The reaction and the analysis of the results were carried out in the same procedures as in application example 3, except that methyl decanoate was used instead of methyl laurate as the reaction raw material and ethyl acetate was used instead of n-octane as the solvent and the diluent, wherein the catalysts used and the results of the gas chromatography analysis after the reaction using the same were shown in table 5.

TABLE 5

Application example 6: modified Me_aX_bAl_cComposite catalyst and different solid acid catalyst compositionsThe combined catalyst is used for catalyzing fatty acid (ester) to prepare branched alkane serving as a main product through hydrodeoxygenation

The reaction and the result analysis were performed in the same procedure as in application example 5 except that the reaction temperature was increased to 240 ℃, wherein the catalysts used and the results of the gas chromatography analysis after the reaction to which they were applied are shown in table 6, and wherein the isomerization rate of alkanes was calculated by the following formula:

TABLE 6

Application example 7: preparation of straight-chain alkane by hydrodeoxygenation of different reaction raw materials

Except that different reaction raw materials as shown in the following Table 7 were used, and Ru/Cu prepared in preparation example 4 was used₃Mn₆Al₁Reaction and result analysis were carried out in the same procedure as in application example 3 except for the composite catalyst composed of the composite catalyst (Ru loading was 0.1%) and the mordenite molecular sieve catalyst, wherein the reaction raw materials used and the gas chromatography analysis results after the reaction thereof are shown in table 7.

TABLE 7

Note: because the raw materials of the jatropha oil, the palm oil, the cottonseed oil and the illegal cooking oil are mixtures, the products after reaction are also corresponding mixtures of various alkanes.

Application example 8: preparation of branched alkane by hydrodeoxygenation of different reaction raw materials

Except that different reaction raw materials as shown in the following Table 7 were used, and Ru/Cu prepared in production example 5 was used₃Mn₆Al₁A composite catalyst (Ru loading 0.1%) and a mordenite molecular sieve catalyst were used, and the reaction and the analysis of the results were carried out in the same manner as in application example 7 except that the reaction temperature was raised to 240 ℃ in which the reaction raw materials used and the color of the gas phase after the reaction were changedThe results of the spectral analysis are shown in Table 8.

TABLE 8

Note: because the raw materials of the jatropha curcas oil, the palm oil, the cottonseed oil and the illegal cooking oil are mixtures, the products after reaction are corresponding mixtures of various alkanes; in addition, since there are many isomeric products, all isomeric products are classified herein according to the number of carbon atoms and provide isomerization rate results.

Application example 9: preparation of alkanes by hydrodeoxygenation of fatty acids (esters) under different reaction conditions

Pd/Fe prepared in preparation example 6 was used except that ethyl stearate was used as a reaction raw material in place of methyl laurate₁Zn₄Al₅The combined catalyst consisting of the composite catalyst (Pd supported 0.3%) and the HX molecular sieve catalyst was subjected to the reaction and the result analysis in the same procedure as in application example 4, using n-dodecane as a solvent and a diluent, and using reaction conditions shown in the following table 9, wherein the reaction conditions used and the results of the gas chromatography analysis after the reaction are shown in table 9.

TABLE 9

Application example 10: preparation of straight-chain alkane by fatty acid (ester) hydrodeoxygenation in different reaction solvents and without solvent

Pt/Ni prepared by preparation example 7 was used except that methyl oleate was used as a reaction raw material instead of methyl laurate₃Mn₆Al₁The reaction and the analysis of the results were performed in the same procedure as in application example 3 except for using a combination catalyst composed of a composite catalyst (Pt loading is 0.5%) and HX molecular sieve catalyst, and using different solvents (and used as a diluent) as shown in the following table 10 or without using a solvent, wherein the solvents used and the results of the gas chromatography analysis after the reaction thereof are shown in table 10.

Watch 10

Solvent(s)	Conversion (%)	Alkane yield (%)
			Water (W)	98.9	98.1
N-hexane	98.9	98.2
			Methanol	98.1	96.9.
Ethanol	99.0	98.1
			Isopropanol (I-propanol)	97.9	97.3
N-octane	98.9	97.9
			Ethyl acetate	98.7	98.0
N-dodecane	97.9	96.9
			N-tetradecane	97.9	97.1
Is free of	95.6	94.0

Application example 11: the branched alkane is prepared by hydrodeoxygenation of fatty acid (ester) in different reaction solvents and without solvents.

The reaction and result analysis were performed in the same procedure as in application example 10 except that the reaction temperature was increased to 240 ℃ or no solvent was used, wherein the catalysts used and the results of gas chromatography analysis after the reaction to which they were applied are shown in table 11, and wherein the isomerization rate of alkanes was calculated by the following formula:

TABLE 11

Solvent(s)	Conversion (%)	Alkane yield (%)	Paraffin isomerization ratio (%)
				Water (W)	98.9	98.1	94.2
N-hexane	98.9	98.2	95.6
				Methanol	98.1	96.9.	97.3
Ethanol	99.0	98.1	98.1
				Isopropanol (I-propanol)	97.9	97.3	93.2
N-octane	98.9	97.9	98.4
				Ethyl acetate	98.7	98.0	98.5
N-dodecane	97.9	96.9	97.2
				N-tetradecane	97.9	97.1	96.1
Is free of	94.8	93.2	95.2

Application example 12: evaluation of the Recycling Properties of the combination catalysts

Pd/Co prepared in preparation example 8 was used except that methyl decanoate was used as the reaction raw material in place of methyl laurate₃Zn₆Al₁Except for the composite catalyst consisting of the composite catalyst (Pd supported 0.3%) and the mordenite molecular sieve, the reaction and the result analysis were performed in the same procedure as in application example 3, and the separated composite catalyst was repeatedly used five times, wherein the results of the gas chromatography analysis after the reaction are respectively shown in table 12.

TABLE 12

Number of catalyst cycles	Conversion (%)	Alkane yield (%)
			1	99.9	99.8
2	99.9	99.1
			3	98.9	98.5
4	97.1	96.8
			5	95.9	94.1

As can be seen from the results of tables 1 to 11 above, by using the combined catalyst of the optional active metal modified composite catalyst of the present invention and the solid acid catalyst, the present invention can prepare a linear or branched alkane product having the same carbon number from a fatty acid or a fatty acid ester by catalytic hydrodeoxygenation, and has excellent raw material conversion rate, product selectivity and yield. In addition, from the reaction results of the application examples 1 to 2 and the application examples 3 to 12, the combined catalyst composed of the composite catalyst modified by the active metal and the solid acid has better stability, catalytic activity and recyclability. In addition, according to the reaction results, the alkane product prepared by the method has good conversion rate and alkane isomerization rate.

The above description of the embodiments is only intended to facilitate the understanding of the method and the core idea of the invention. In addition, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention as defined in the appended claims.

Claims

1. A process for the catalytic hydrodeoxygenation of fatty acids and/or fatty acid esters to same carbon number alkanes, said process comprising: in a reaction vessel, in the presence of a catalyst, at a low temperature of 100-300 ℃ and a low hydrogen pressure of 0.1-5 MPa, the fatty acid and/or the fatty acid ester and hydrogen are subjected to hydrodeoxygenation reaction to obtain a required alkane product with the same carbon number,

2. The method according to claim 1, characterized in that said Me_aX_bAl_cThe composite catalyst is modified by active metal, wherein the active metal is one or more selected from Pd, Ru, Pt, Co, Ir, Os, Rh, Ag and Cu.

3. The method according to claim 2, characterized in that based on said Me_aX_bAl_cThe weight of the composite catalyst, the content of the active metal is 0.01-10.0%.

4. The method according to claim 2, characterized in that it is based on said Me_aX_bAl_cThe weight of the composite catalyst, the content of the active metal is 0.1-3.0%.

5. Method according to claim 1 or 2, characterized in that said Me_aX_bAl_cThe composite catalyst is subjected to pre-reduction treatment in a hydrogen atmosphere before use, or is directly subjected to in-situ reduction treatment in the hydrogen atmosphere of a reaction vessel.

6. The method according to claim 1 or 2, characterized in that the fatty acids and/or fatty acid esters are saturated or unsaturated C6-C22 fatty acids and/or fatty acid esters.

7. The method of claim 6, wherein the fatty acid is one or more selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, tetradecenoic acid, 2-enoic acid, palmitic acid, palmitoleic acid, hexadecanoic acid, 2, 4-dienoic acid, palmitic acid, oleic acid, linoleic acid, stearic acid, linoleic acid, arachidic acid, erucic acid, and behenic acid; the fatty acid ester is one or more selected from methyl decanoate, methyl laurate, methyl palmitate, ethyl oleate, methyl oleate, ethyl stearate, jatropha oil, palm oil, coconut oil, cottonseed oil and illegal cooking oil.

8. The process according to claim 6, wherein the feed molar ratio of the catalyst to the fatty acid and/or fatty acid ester is 1:1 to 100.

9. The process according to claim 6, wherein the feed molar ratio of the catalyst to the fatty acid and/or fatty acid ester is 1:10 to 100.

10. the method of claim 1 or 2, wherein the molecular sieve is an HZSM-5 molecular sieve, an HY zeolite molecular sieve, an H β zeolite molecular sieve, a mordenite, an HX zeolite molecular sieve, a ZSM-35 molecular sieve, a SAPO-34 molecular sieve or a SAPO-11 molecular sieve, and the metal oxide is Al₂O₃、SiO₂Or Nb₂O₅(ii) a The solid super acid is SO₄ ^2-/ZrO₂、WO₃/ZrO₂Or MoO₃/ZrO₂。

11. The method according to claim 1 or 2, wherein the hydrodeoxygenation reaction is carried out in the absence of a solvent or in the presence of a solvent, and the time of the hydrodeoxygenation reaction is 0.5 to 24 hours.

12. The method of claim 11, wherein the solvent is one or more selected from the group consisting of water, n-hexane, methanol, ethanol, isopropanol, n-octane, ethyl acetate, methyl acetate, dodecane, and tetradecane.

13. The method according to claim 1 or 2, wherein the hydrodeoxygenation reaction is carried out at 100-200 ℃ to obtain a main product of straight-chain alkane with the same carbon number.

14. The method according to claim 1 or 2, wherein the hydrodeoxygenation reaction is carried out at 200-300 ℃ to obtain a main product of branched alkanes with the same carbon number.

15. The method according to claim 1, characterized in that said Me_aX_bAl_cThe composite catalyst was prepared as follows:

mixing soluble salts of metals Me, X and Al in water according to a composition molar ratio, and then adding an alkali solution to obtain a precipitate;

the precipitate obtained is calcined and finally reduced to give the desired Me_aX_bAl_cA composite catalyst.

16. The method according to claim 2, characterized in that said active metal modified Me_aX_bAl_cThe composite catalyst was prepared as follows:

mixing soluble salts of metals Me, X and Al in water in a compositional molar ratio, then adding an alkali solution to obtain a precipitate, and calcining the obtained precipitate to obtain Me_aX_bAl_cA complex;

the obtained Me_aX_bAl_cThe complex is dispersed in a solvent, then a soluble salt of the active metal is added and mixed with sufficient agitation to load the active metal to Me_aX_bAl_cCompoundingOn the object;

the obtained Me carrying active Metal_aX_bAl_cDrying the compound and reducing to obtain the required active metal modified Me_aX_bAl_cA composite catalyst.

17. The method according to claim 15 or 16, wherein the alkali solution is a sodium hydroxide, potassium hydroxide, sodium carbonate or aqueous ammonia solution; the soluble salt is a nitrate, acetate or chloride salt.

18. Method according to claim 16, characterized by dispersing said Me_aX_bAl_cThe solvent of the complex is water, ethanol, acetone, diethyl ether, toluene or xylene.

19. The process of claim 1 or 2, wherein the combined catalyst is recycled.